The present invention relates to laser cavities. Such optical cavities resonated by a laser source, i.e. a laser diode, can select one or more wavelengths emitted by a laser amplifier medium. Known cavities frequently comprise two mirrors, one constituting a cavity end element and the other constituting a tuning element for tuning the laser. For providing a single mode laser the cavity furthermore can contain a wavelength filter, e.g. a diffraction grating, for selecting a certain wavelength. Cavities containing such a filter can be built up according to the Littrow- or the Littman-configuration as disclosed in U.S. Pat. No. 5,594,744 or in U.S. Pat. No. 6,252,718, for example.